Heinrich Ernst Gotter
Referred to only as "M. de Gotter" by Boswell, but tentatively identified by the editors of the Journal of his German and Swiss Travels as Henrich Ernst Gotter, who was Master of Rolls (1735-), Counsellor of Legation (1743-) and Head of the Privy Council's secretariat (1752-1772) in Gotha.
Gotter married firstly (xxxx) ??? and secondly (1762) Madeleine von Wangerheim. One of his sons was the poet Friedrich Wilhelm Gotter (1746-1797).
Boswell had a recommendation to see Gotter in Gotha on October 17, 1764, but Gotter was out of town at the time, and the two probably never met.